With "rebuilt" parts being the more typical repair work done these days, few get into the machine work themselves any more.
My experience with major engine work comes from motorcycles, where repair was always done since "rebuilt" parts (like heads) didn't exist.
On those, we only cut seats & lapped valves in B4 final assembly - any bad valves had to be replaced not reground since they originally were hard faced (stellite) from the factory, and re-ground valves would have a softer face & wear quickly.
Amazing how valve adjustment intervals have gone from regular to never isn't it? Even without automatic adjusters it's gotten to the point they seem to figure the engine will wear out B4 it's needed....
If regrinding is appropriate for the Focus valves, amc's suggestions on tip grinding if needed, combined with swapping buckets may be enough to do the job without buying a bunch of new buckets. More labor, less parts $. Depends who's doing all the labor as to what's the cheapest route!